Compass



July 16, 1940.

E. WARNER COMPASS Filed Jan. 10, 1938 v110 ing work.

Patented July 16, 1940 UNITED STATES PATENT OFFICE Application January 10,

12 Claims.

This invention relates to compasses and similar instruments such as dividers, calipers, and the like.

One object of the invention is to provide an instrument of this type which shall be accurate and durable, yet cheaply constructed and easily assembled, an instrument which is designed for mass production so it can be sold for a low price and is yet suitable for the highest class of draft- Another object is the provision of a novel and simplified hinge joint having means for maintaining the handle of the instrument always at equal angles with the compass legs-irrespective of the degree of separation of the legs thus providing a simple form of what is called a straightener head.

A further object is the provision of means whereby the proper friction of the head plates is constantly maintained, so that the instrument will remain in any position in which it is set, thus making the instrument adaptable to precision drafting work.

Other objects of the invention will be apparent from the following specification, wherein my invention will be described with reference to the accompanying drawing in which:

Fig. l is a front view of a preferred form of my improved compass.

Fig. 2 is a side iew of the instrument illustrated in Fig. l.

3 is a section taken on line 3-3 of Fig. 1.

Fig. 4 is a perspective View of one leg of the compass shown in Fig. 1, illustrating the integral form of the hinge pin.

Fig. 5 is a perspective view of the spring yoke used on the same instrument.

Fig. 6 is a similar View of an alternative yoke structure.

Fig. 7 is a front View of an alternative form of leg.

Fig. 3 is a side view of the leg shown in Fig. '7.

Fig. 9 is an enlarged section taken on line 9-9 of Fig. '7. V

Fig. 10 is an enlarged section taken on a line it--iil of Fig. 7.

Referring first to Figs. 1 to 5 it will be seen that my compass comprises legs H and I2 which in the preferred form are die castings which require no further machining. These legs are hinged together at it by a hinge pin M which is cast integrally with the head plate and the leg i2. Pin M is adapted to fit in hole l6 in head plate .ll cast integrally with leg ll. Hole It may 1938, Serial No. 184,140

but need not extend completely through head plate ii.

The hinge is held together by a spring yoke l8 which carries the handle H) which is advantageously screwed or riveted into a suitable hole in yoke l8. This yoke is made of a resilient material, preierably spring steel, and is formed in what is substantially a U shape, in such manner that the sides tend to converge towards their free ends, illustratedin Fig. 5. The ends of the yoke must thus be sprung apart in order that it may be placed over the head plates i5 and ll of legs It and 62. When in place it therefore holds the hinge together under a gentle but firm pressure which produces the necessary friction in the hinge.

This spring tension causes the compass to retain its setting and draw true and accurate circles without the necessity of a close and accurate fit of hinge pin it in hole It. This not only removes the necessity of expensive and accurate work in manufacture but automatically compensates for any wear which may take place in prolonged use. Thus it not only reduces the cost of production but greatly prolongs the useful life of the instrument, and by removing the necessity for adjustment, gives the instrument a phenomenally long useful life even in the hands of the unskilled.

Provision is also made for holding the yoke IS in place on the hinge i3 and for maintaining it always at equal angles with the two legs to form what is known as a straightener head. For these purposes lugs 26 and 22 are provided symmetrically located on and preferably cast integral withhead plates i5 and il respectively, of legs [2 and l 1. Channels 23 and 24 are formed in symmetrical positions on opposite sides of yoke It, so that when assembled they fit over the lugs 21 and 22. Yoke I8 is thus prevented from sliding off of the hinge i3. It will also be seen that as the legs H and i 2 are spread on the hinge, lugs 2i and 22 will move downward at the same rate, thus moving yoke l8 downward but maintaining it in its vertical position, i. on a line which bisects the angle between legs i I and i2. When the legs are moved towards each other on the hinge the opposite action will obviously take place, with the handle still maintaining its vertical position.

The lower ends of legs ii and 12 are. slotted as shown at 3i and 32, respectively. Slots 3! and 32 are provided On their opposite sides with grooves 33 and 34 respectively which are adapted to receive round objects as needles, leads, etc., of whatever size desired. In order to make the instrument most useful I prefer to make the grooves in one leg of a size which can be adjusted to hold a standard phonograph needle or a standard pencil lead, and those in the other leg slightly smaller so they can be adjusted to hold a standard phonograph needle or a regular thin pencil lead. Thus it is possible to put needles into both legs making the instrument into a pair of dividers or to replace one needle or the other with a standard or thin pencil lead and use it for drawing circles or circle arcs. It is thus possible for any person to readily secure fresh leads or needles at any time, which is a great advantage to the owner of the instrument.

The grooves 33 and 34 may be formed at any desired angles 25 and 26 with legs ll and 12 respectively. If the angles are small, i. e., if the needle and lead are nearly in line. with the legs it lowers the upper limit and raises thelower limit to the sizes of circles which can be drawn with the instrument. If the angle is large, large circles can be drawn conveniently but in drawing small circles the needle and pencil points are so far from perpendicular to the paper that they do not work well. I find angles between 10 and degrees are advisable, but an angle in the neighborhood of 20 degrees is most advantageous in that it gives the greatest range of radii for which the instrument can conveniently be used. It is also possible to use angles less than 10 degrees or more than 30 degrees on special instruments designed for limited ranges of radii. I also find it advantageous, but not necessary, that the angles on the two legs should be equal.

To clamp leads and needles firmly in place T head bolts 35 and 36 with thumb nuts 3'! and 38 are provided. The T heads are held against rotion by rectangular countersinks 39 like that shown in leg l2 in Fig. 4.

Although I prefer the form and methods of manufacture described numerous changes in structure can be made within the scope of the appended claims. For example, the spring yoke can be made with slots, as 43 and 44 (Fig. 6) instead of'the channels 23 and 24, used in the form described, to receive lugs 2| and 22 on the head plates of the legs.

Instead of making the legs in the form of die castings they may be punched from sheet metal as illustrated in Figs. 7 to 10 inclusive. As shown in this drawing the head plates 55 are made of a single thickness of metal while the body of the leg 52 is formed by folding the metal over double as shown in Fig. 9. The hinge pin 54 is formed by pressure, indenting the other side as shown at 53. The lugs 6 I can be formed in the same manner, or by bending as illustrated in Figs. '7 and 8. The hole in the other leg (not shown) for co-operating with hinge pin 54 can be formed by a simple punching operation. The slit 1! in the end of the legs is formed as illustrated by a simple termination of the fold in the metal. The grooves 13 for holding needles and leads, and the holes for the T head bolts are made as shown in Fig. 10 by a punching and forming operation.

I have illustrated a compass as made with one piece legs, and I find that with legs only 3% inches long having the grooves 33 and 34 placed at the proper angle it is possible to use such compass for drawing circles from a diameter less than inch to one of over 13 inches. Nevertheless, if desired, legs with known forms of knee joints can be used with my invention. I prefer, however, the form illustrated because of its great range, simplicity, and superior rigidity of construction. Other modifications in the details of construction can also be made by those skilled in the art without departing from the spirit of the present invention.

Further I do not wish to be understood as limiting my compass to any specific size or proportion as any practicable size of instrument can be constructed in accordance with the present invention.

Neither do I wish to be understood as limiting the use of my invention to compasses, strictly so called, as various features of novelty defined in the appended claims can be advantageously applied to the construction of dividers, calipers, and other purposes where mechanisms of this kind are required.

I claim:

1. A compass comprising two legs, a head plate cast integrally with each of said legs, said head plates being complementary in form and together forming a hinge joint, a flexible spring yoke for yieldingly holding said head plates together to maintain the hinged relationship, a slit formed in the opposite end of each leg, each slit having an enlarged channel therethrough, a bolt hole having one end so formed as to hold a T head bolt, extending through each leg near the extremity.

2. A compass comprising two legs, a head plate formed integrally with each leg, an integral hinge pin projecting from one of said head plates, a cooperating hole in the other head plate, a spring yoke straddling and holding together the assembly of said two plates, a lug projecting from each of said plates, a channel in each side of said yoke, said channels being adapted to fit over said projecting lugs to hold said yoke in place and to cause said yoke to always form approximately equal angles with said legs.

3. A compass comprising two one piece legs, a head plate formed integral with each leg, cooperating hinge elements formed integral with said head plates, and a flexible spring yoke adapted to yieldingly hold said hinge elements in operative engagement.

4. A hinge for a compass, comprising two head plates, a hinge pin formed integrally with one plate, a co-operating hole formed in the other plate, a flexible spring yoke adapted to hold said parts in co-operative relation, and to produce relatively large frictional resistance to operation of the hinge, and means for holding said yoke in place.

5. A hinge for a compass comprising two head plates, a hinge pin formed integrally with one plate, a co-operating hole in the other plate, and a flexible spring yoke adapted to hold said parts in co-operative relation.

' 6. A hinge joint for a compass, comprising head plates formed integrally with the legs of the compass, complementary pivot means formed in said head plates, a spring yoke for holding said pivot means in engagement, and means for holding said yoke in place, said yoke possessing sufficient flexibility to permit it to be sprung into operative position.

'7. A straightener head for a compass, comprising a head plate on one compass leg, a complementary head plate on the other compass leg, 'a flexible spring yoke adapted to yieldingly hold said head plates together, symmetrical sliding connections between said head plates and said yoke, said connections being adapted to hold said yoke in place and at approximately equal angles with the legs of the compass.

'8. A straightener head for a compass comprising a head plate formed on each leg of the compass, a hinge joint pivotally connecting said head plates, a yoke, and symmetrical sliding connections between said yoke and each of said head plates, said sliding connections being formed by a sliding element formed integrally with each of said head plates and symmetrically disposed with reference to that on the other head plate, and cooperating sliding elements formed integrally with said yoke.

9. A straightener head for a compass, comprising a head plate on one compass leg, a complementary head plate on the other compass leg, a yoke, a projection from each of said head plates, symmetrically located with respect to each other, and slideways in said yoke adapted to cooperate with said projections to maintain approximately equal angles between said yoke and each of said legs.

10. A yoke for a compass hinge comprising a flat piece of spring steel formed into substantially a U shape in which the sides tend to converge towards their free ends and in which guides are formed to receive protruding portions of the compass hinge and thereby hold the yoke in place thereon.

l1. A compass leg having a head plate formed integrally therewith at one end thereof, said head plate having a hinge element adapted to cooperate with a complementary element on another leg, formed integrally therewith on one side thereof and an eccentrically located projection formed integrally therewith on the other side thereof, a slit in the other end, and a channel passing through said slit and forming an angle of approximately 20 degrees with the center line of said leg.

12. A compass comprising two legs, an axially separable hinge composed solely of integral parts of said legs, for maintaining said legs in hinged relationship, and a flexible spring yoke which exerts an axially directed pressure on said hinge and thereby yieldingly holds said parts against axial separation.

EDGAR WARNER. 

